miiphy: constify device name

The driver name does not need to be writable, so constify it.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Ben Warren <biggerbadderben@gmail.com>
diff --git a/board/evb64260/eth.c b/board/evb64260/eth.c
index 8d1b606..a96e655 100644
--- a/board/evb64260/eth.c
+++ b/board/evb64260/eth.c
@@ -89,7 +89,7 @@
 /* MII PHY access routines are common for all i/f, use gal_ent0 */
 #define GT6426x_MII_DEVNAME	"gal_enet0"
 
-int gt6426x_miiphy_read(char *devname, unsigned char phy,
+int gt6426x_miiphy_read(const char *devname, unsigned char phy,
 		unsigned char reg, unsigned short *val);
 
 static inline unsigned short
@@ -345,7 +345,7 @@
 MII utilities - write: write to an MII register via SMI
 ***************************************************************************/
 int
-gt6426x_miiphy_write(char *devname, unsigned char phy,
+gt6426x_miiphy_write(const char *devname, unsigned char phy,
 		unsigned char reg, unsigned short data)
 {
     unsigned int temp= (reg<<21) | (phy<<16) | data;
@@ -360,7 +360,7 @@
 MII utilities - read: read from an MII register via SMI
 ***************************************************************************/
 int
-gt6426x_miiphy_read(char *devname, unsigned char phy,
+gt6426x_miiphy_read(const char *devname, unsigned char phy,
 		unsigned char reg, unsigned short *val)
 {
     unsigned int temp= (reg<<21) | (phy<<16) | 1<<26;